1. Field of the Invention
The present invention relates to a slide fastener, and more particularly to a fluid-tight slide fastener stringer.
2. Prior Art
There are known various fluid-tight slide fasteners. One such fluid-tight slide fastener includes a stringer tape which supports edgewisely a row of continuous coupling elements on one side and a sealing member on the other side. For example a fluid-tight slide fastener of this type is disclosed by U.S. Pat. No. 3,501,816 as shown in FIG. 9 of the accompanying drawings. This slide fastener produces a seal when a pair of rows of coupling elements 102 are coupled underneath the coplanar stringer tapes 101 urging opposed sealing lips 104 to bear against each other above the tapes 101. Each of the sealing lips 104 formed into a wedge-shaped projection is raised from a general plane of the coplanar tapes 101 with the result that the sealing lips 104 neccessarily bear upon each other with a sealing force directed at a level remote from a level at which the coupling elements 102 are intermeshed together. In this mutually compressed relation, only the tapes 101 support the opposing sealing lips 104. The supporting tapes 101, however, fail to support the same strongly enough to keep the sealing force unidirectional and parallel to the general plane of the tapes to obtain most effective seal against leakage.
Another type of fluid-tight slide fastener is disclosed by Japanese Utility Model Publication (Jikkosho) No. 55-31939. This prior fastener as shown in FIG. 10 includes a pair of stringer tapes 201, each having a row of discrete coupling elements 203 each bracketing a longitudinally folded edge 202 of the tape 201 and a sealing member 204 underlying the latter for thereby allowing the sealing members 204 to be sandwiched tightly in between the elements rows and the folded tape edges. However, each one of the discrete coupling elements 203 has a bracketing structure 203a which adds to the cost of manufacture of the slide fastener products and also impairs the appearance of an article to which the fastener is attached.